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Medicina (Kaunas, Lithuania) Sep 2023Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects both the upper and lower motor neurons in the nervous system, causing muscle...
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects both the upper and lower motor neurons in the nervous system, causing muscle weakness and severe disability. The progressive course of the disease reduces the functional capacity of the affected patients, limits daily activities, and leads to complete dependence on caregivers, ultimately resulting in a fatal outcome. Respiratory dysfunction mostly occurs later in the disease and is associated with a worse prognosis. Forty-six participants were included in our study, with 23 patients in the ALS group and 23 individuals in the control group. The ultrasound examination of the phrenic nerve (PN) was performed by two authors using a high-resolution "Philips EPIQ 7" ultrasound machine with a linear 4-18 MHz transducer. Our study revealed that the phrenic nerve is significantly smaller on both sides in ALS patients compared to the control group ( < 0.001). Only one significant study on PN ultrasound in ALS, conducted in Japan, also showed significant results ( < 0.00001). These small studies are particularly promising, as they suggest that ultrasound findings could serve as an additional diagnostic tool for ALS.
Topics: Humans; Amyotrophic Lateral Sclerosis; Phrenic Nerve; Neurodegenerative Diseases; Prognosis; Muscle Weakness
PubMed: 37893463
DOI: 10.3390/medicina59101745 -
Journal of Neurophysiology Sep 2021Plasticity is a hallmark of the respiratory neural control system. Phrenic long-term facilitation (pLTF) is one form of respiratory plasticity characterized by...
Plasticity is a hallmark of the respiratory neural control system. Phrenic long-term facilitation (pLTF) is one form of respiratory plasticity characterized by persistent increases in phrenic nerve activity following acute intermittent hypoxia (AIH). Although there is evidence that key steps in the cellular pathway giving rise to pLTF are localized within phrenic motor neurons (PMNs), the impact of AIH on the strength of breathing-related synaptic inputs to PMNs remains unclear. Furthermore, the functional impact of AIH is enhanced by repeated/daily exposure to AIH (dAIH). Here, we explored the effects of AIH versus 2 wk of dAIH preconditioning on spontaneous and evoked phrenic responses in anesthetized, paralyzed, and mechanically ventilated rats. Evoked phrenic potentials were elicited by respiratory cycle-triggered lateral funiculus stimulation at the C2 spinal level delivered before and 60 min post-AIH (or the equivalent in time controls). Charge-balanced biphasic pulses (100 μs/phase) of progressively increasing intensity (100-700 μA) were delivered during the inspiratory and expiratory phases of the respiratory cycle. Although robust pLTF (∼60% from baseline) was observed after a single exposure to moderate AIH (3 × 5 min; 5-min intervals), there was no effect on evoked phrenic responses, contrary to our initial hypothesis. However, in rats preconditioned with dAIH, baseline phrenic nerve activity and evoked responses were increased, suggesting that repeated exposure to AIH enhances functional synaptic strength when assessed using this technique. The impact of daily AIH preconditioning on synaptic inputs to PMNs raises interesting questions that require further exploration. Two weeks of daily acute intermittent hypoxia (dAIH) preconditioning enhanced stimulus-evoked phrenic responses to lateral funiculus stimulation (targeting respiratory bulbospinal projection to phrenic motor neurons). Furthermore, dAIH preconditioning enhanced baseline phrenic motor output responses to maximal chemoreflex activation in intact rats.
Topics: Animals; Evoked Potentials; Hypoxia; Male; Motor Neurons; Neuronal Plasticity; Phrenic Nerve; Rats; Rats, Sprague-Dawley
PubMed: 34260289
DOI: 10.1152/jn.00112.2021 -
Respiratory Physiology & Neurobiology Jun 2016Integrated electrical activity in the phrenic nerve is commonly used to assess within-animal changes in phrenic motor output. Because of concerns regarding the... (Meta-Analysis)
Meta-Analysis
Integrated electrical activity in the phrenic nerve is commonly used to assess within-animal changes in phrenic motor output. Because of concerns regarding the consistency of nerve recordings, activity is most often expressed as a percent change from baseline values. However, absolute values of nerve activity are necessary to assess the impact of neural injury or disease on phrenic motor output. To date, no systematic evaluations of the repeatability/reliability have been made among animals when phrenic recordings are performed by an experienced investigator using standardized methods. We performed a meta-analysis of studies reporting integrated phrenic nerve activity in many rat groups by the same experienced investigator; comparisons were made during baseline and maximal chemoreceptor stimulation in 14 wild-type Harlan and 14 Taconic Sprague Dawley groups, and in 3 pre-symptomatic and 11 end-stage SOD1(G93A) Taconic rat groups (an ALS model). Meta-analysis results indicate: (1) consistent measurements of integrated phrenic activity in each sub-strain of wild-type rats; (2) with bilateral nerve recordings, left-to-right integrated phrenic activity ratios are ∼1.0; and (3) consistently reduced activity in end-stage SOD1(G93A) rats. Thus, with appropriate precautions, integrated phrenic nerve activity enables robust, quantitative comparisons among nerves or experimental groups, including differences caused by neuromuscular disease.
Topics: Amyotrophic Lateral Sclerosis; Animals; Chemoreceptor Cells; Disease Models, Animal; Humans; In Vitro Techniques; Male; Microelectrodes; Phrenic Nerve; Rats, Sprague-Dawley; Rats, Transgenic; Reflex; Reproducibility of Results; Respiration; Species Specificity; Superoxide Dismutase-1
PubMed: 26724605
DOI: 10.1016/j.resp.2015.12.005 -
Respiratory Physiology & Neurobiology Oct 2011Intermittent hypoxia-induced long-term facilitation (LTF) is variably expressed in the motor output of several inspiratory nerves, such as the phrenic and hypoglossal.... (Comparative Study)
Comparative Study Review
Intermittent hypoxia-induced long-term facilitation (LTF) is variably expressed in the motor output of several inspiratory nerves, such as the phrenic and hypoglossal. Compared to phrenic LTF (pLTF), less is known about hypoglossal LTF (hLTF), although it is often assumed that cellular mechanisms are the same. While fundamental mechanisms appear to be similar, potentially important differences exist in the modulation of pLTF and hLTF. The primary objectives of this paper are to: (1) review similarities and differences in pLTF and hLTF, pointing out knowledge gaps and (2) present new data suggesting that reduced respiratory neural activity elicits differential plasticity in phrenic and hypoglossal output (inactivity-induced phrenic and hypoglossal motor facilitation, iPMF and iHMF), suggesting that these motor pool-specific differences are not unique to LTF. Differences in fundamental mechanisms or modulation of plasticity among motor pools may confer the capacity to mount a complex ventilatory response to specific challenges, particularly in motor pools with different "jobs" in the control of breathing.
Topics: Animals; Humans; Hypoglossal Nerve; Motor Neurons; Phrenic Nerve; Respiratory Mechanics
PubMed: 21745601
DOI: 10.1016/j.resp.2011.06.022 -
Clinical Anatomy (New York, N.Y.) Mar 2020The contribution of the left phrenic nerve to innervation of the esophagogastric junction. The esophagogastric junction is part of the barrier preventing...
The contribution of the left phrenic nerve to innervation of the esophagogastric junction. The esophagogastric junction is part of the barrier preventing gastroesophageal reflux. We have investigated the contribution of the phrenic nerves to innervation of the esophagogastric junction in humans and piglets by dissecting 30 embalmed human specimens and 14 piglets. Samples were microdissected and nerves were stained and examined by light and electron microscopy. In 76.6% of the human specimens, the left phrenic nerve participated in the innervation of the esophagogastric junction by forming a neural network together with the celiac plexus (46.6%) or by sending off a distinct phrenic branch, which joined the anterior vagal trunk (20%). Distinct left phrenic branches were always accompanied by small branches of the left inferior phrenic artery. In 10% there were indirect connections with a distinct phrenic nerve branch joining the celiac ganglion, from which celiac plexus branches to the esophagogastric junction emerged. Morphological examination of phrenic branches revealed strong similarities to autonomic celiac plexus branches. There was no contribution of the left phrenic nerve or accompanying arteries from the caudal phrenic artery in any of the piglets. The right phrenic nerve made no contribution in any of the human or piglet samples. We conclude that the left phrenic nerve in humans contributes to the innervation of the esophagogastric junction by providing ancillary autonomic nerve fibers. Experimental studies of the innervation in pigs should consider that neither of the phrenic nerves was found to contribute. Clin. Anat. 33:265-274, 2020. © 2019 Wiley Periodicals, Inc.
Topics: Aged; Aged, 80 and over; Anatomic Variation; Animals; Cadaver; Celiac Plexus; Esophagogastric Junction; Female; Humans; Male; Microscopy, Electron; Phrenic Nerve; Swine; Vagus Nerve
PubMed: 31625208
DOI: 10.1002/ca.23502 -
Annals of Biomedical Engineering Apr 2016The primary goal of this computational modeling study was to better quantify the relative distance of the phrenic nerves to areas where cryoballoon ablations may be...
The primary goal of this computational modeling study was to better quantify the relative distance of the phrenic nerves to areas where cryoballoon ablations may be applied within the left atria. Phrenic nerve injury can be a significant complication of applied ablative therapies for treatment of drug refractory atrial fibrillation. To date, published reports suggest that such injuries may occur more frequently in cryoballoon ablations than in radiofrequency therapies. Ten human heart-lung blocs were prepared in an end-diastolic state, scanned with MRI, and analyzed using Mimics software as a means to make anatomical measurements. Next, generated computer models of ArticFront cryoballoons (23, 28 mm) were mated with reconstructed pulmonary vein ostias to determine relative distances between the phrenic nerves and projected balloon placements, simulating pulmonary vein isolation. The effects of deep seating balloons were also investigated. Interestingly, the relative anatomical differences in placement of 23 and 28 mm cryoballoons were quite small, e.g., the determined difference between mid spline distance to the phrenic nerves between the two cryoballoon sizes was only 1.7 ± 1.2 mm. Furthermore, the right phrenic nerves were commonly closer to the pulmonary veins than the left, and surprisingly tips of balloons were further from the nerves, yet balloon size choice did not significantly alter calculated distance to the nerves. Such computational modeling is considered as a useful tool for both clinicians and device designers to better understand these associated anatomies that, in turn, may lead to optimization of therapeutic treatments.
Topics: Cryosurgery; Heart Atria; Humans; Magnetic Resonance Imaging; Models, Biological; Phrenic Nerve; Pulmonary Veins
PubMed: 26168718
DOI: 10.1007/s10439-015-1379-3 -
European Journal of Cardio-thoracic... Apr 2016The importance of phrenic nerve preservation during pneumonectomy remains controversial. We previously demonstrated that preservation of the phrenic nerve in the...
OBJECTIVES
The importance of phrenic nerve preservation during pneumonectomy remains controversial. We previously demonstrated that preservation of the phrenic nerve in the immediate postoperative period preserved lung function by 3-5% but little is known about its long-term effects. We, therefore, decided to investigate the effect of temporary ipsilateral cervical phrenic nerve block on dynamic lung volumes in mid- to long-term pneumonectomy patients.
METHODS
We investigated 14 patients after a median of 9 years post pneumonectomy (range: 1-15 years). Lung function testing (spirometry) and fluoroscopic and/or sonographic assessment of diaphragmatic motion on the pneumonectomy side were performed before and after ultrasonographic-guided ipsilateral cervical phrenic nerve block by infiltration with lidocaine.
RESULTS
Ipsilateral phrenic nerve block was successfully achieved in 12 patients (86%). In the remaining 2 patients, diaphragmatic motion was already paradoxical before the nerve block. We found no significant difference on dynamic lung function values (FEV1 'before' 1.39 ± 0.44 vs FEV1 'after' 1.38 ± 0.40; P = 0.81).
CONCLUSIONS
Induction of a temporary diaphragmatic palsy did not significantly influence dynamic lung volumes in mid- to long-term pneumonectomy patients, suggesting that preservation of the phrenic nerve is of greater importance in the immediate postoperative period after pneumonectomy.
Topics: Adult; Aged; Female; Humans; Lung; Male; Middle Aged; Nerve Block; Organ Sparing Treatments; Phrenic Nerve; Pneumonectomy; Postoperative Complications
PubMed: 26405235
DOI: 10.1093/ejcts/ezv334 -
Respiratory Care May 2023Mechanical ventilation is widely used in ICU patients as a lifesaving intervention. Diaphragmatic atrophy and thinning occur from lack of contractions of the diaphragm...
BACKGROUND
Mechanical ventilation is widely used in ICU patients as a lifesaving intervention. Diaphragmatic atrophy and thinning occur from lack of contractions of the diaphragm during mechanical ventilation. It may prolong weaning and increase the risk of respiratory complications. Noninvasive electromagnetic stimulation of the phrenic nerves may ameliorate the atrophy seen with ventilation. The objective of this study was to show that noninvasive repetitive electromagnetic stimulation is safe, feasible, and effective to stimulate the phrenic nerves in both awake individuals and anesthetized patients.
METHODS
A single-center study with 10 subjects overall, 5 awake volunteers and 5 anesthetized subjects. We used a prototype electromagnetic, noninvasive, simultaneous bilateral phrenic nerve stimulation device in both groups. In the awake volunteers, we assessed time-to-first capture of the phrenic nerves and safety measures, such as pain, discomfort, dental paresthesia, and skin irritation. In the anesthetized subjects, time-to-first capture as well as tidal volumes and airway pressures at 20%, 30%, and 40% stimulation intensity were assessed.
RESULTS
Diaphragmatic capture was achieved in all the subjects within a median (range) of 1 min (1 min to 9 min 21 s) for the awake subjects and 30 s (20 s to 1 min 15 s) for the anesthetized subjects. There were no adverse or severe adverse events in either group, nor any dental paresthesia, skin irritation, or subjective pain in the stimulated area. Tidal volumes increased in all the subjects in response to simultaneous bilateral phrenic nerve stimulation and increased gradually with increasing stimulation intensity. Airway pressures corresponded to spontaneous breathing of ∼2 cm HO.
CONCLUSIONS
Noninvasive phrenic nerve stimulation can be safely performed in awake and anesthetized individuals. It was feasible and effective in stimulating the diaphragm by induction of physiologic and scalable tidal volumes with minimum positive airway pressures.
Topics: Humans; Phrenic Nerve; Feasibility Studies; Paresthesia; Respiration, Artificial; Diaphragm; Pain
PubMed: 36878642
DOI: 10.4187/respcare.10568 -
Scientific Reports Aug 2018Communicating fibres between the phrenic nerve and sympathetic nervous system may exist, but have not been characterized histologically and immunohistochemically, even...
Communicating fibres between the phrenic nerve and sympathetic nervous system may exist, but have not been characterized histologically and immunohistochemically, even though increased sympathetic activity due to phrenic nerve stimulation for central sleep apnoea may entail morbidity and mortality. We, therefore, conducted a histological study of the phrenic nerve to establish the presence of catecholaminergic fibres throughout their course. The entire phrenic nerves of 35 formalin-fixed human cadavers were analysed morphometrically and immunohistochemically. Furthermore, the right abdominal phrenic nerve was serially sectioned and reconstructed. The phrenic nerve contained 3 ± 2 fascicles in the neck that merged to form a single fascicle in the thorax and split again into 3 ± 3 fascicles above the diaphragm. All phrenic nerves contained catecholaminergic fibres, which were distributed homogenously or present as distinct areas within a fascicle or as separate fascicles. The phrenicoabdominal branch of the right phrenic nerve is a branch of the celiac plexus and, therefore, better termed the "phrenic branch of the celiac plexus". The wall of the inferior caval vein in the diaphragm contained longitudinal strands of myocardium and atrial natriuretic peptide-positive paraganglia ("caval bodies") that where innervated by the right phrenic nerve.
Topics: Abdomen; Autonomic Pathways; Diaphragm; Female; Humans; Male; Neck; Phrenic Nerve; Thorax
PubMed: 30076368
DOI: 10.1038/s41598-018-30145-x -
Journal of Orthopaedic Surgery (Hong... 2023In complete brachial plexus injury, phrenic nerve (PN) is frequently used in neurotization for elbow flexion restoration. The advancement in video-assisted thoracoscopic... (Comparative Study)
Comparative Study Observational Study
BACKGROUND
In complete brachial plexus injury, phrenic nerve (PN) is frequently used in neurotization for elbow flexion restoration. The advancement in video-assisted thoracoscopic surgery (VATS) allows full-length PN dissection intrathoracically for direct coaptation to recipient without nerve graft.
PURPOSE
We report our experience in improving the surgical technique and its outcome.
METHODS
Seven patients underwent PN dissection via VATS and full-length transfer to musculocutaneous nerve (MCN) or motor branch of biceps (MBB) from June 2015 to June 2018. Comparisons were made with similar group of patients who underwent conventional PN transfer.
RESULTS
Mean age of patients was 21.9 years. All were males involved in motorcycle accidents who sustained complete brachial plexus injury. We found the elbow flexion recovery were earlier in full-length PN transfer. However, there was no statistically significant difference in elbow flexion strength at 3 years post-surgery.
CONCLUSION
We propose full-length PN transfer for restoration of elbow flexion in patients with delayed presentation.
Topics: Phrenic Nerve; Nerve Transfer; Elbow Joint; Thoracic Surgery, Video-Assisted; Prospective Studies; Humans; Male; Adolescent; Young Adult; Treatment Outcome
PubMed: 37256763
DOI: 10.1177/10225536231180330